原式=(3/x)+6/(x-1)-(x+5)/(x²-x)
=3(x-1)/(x²-x)+6x(x²-x)-(x+5)/(x²-x)
=[3(x-1)+6x-(x+5)]/(x²-x)
=(3x-3+6x-x-5)/(x²-x)
=(8x-8)/(x²-x)
=8(x-1)/[x(x-1)]
=8/x